1. Field of the Invention
The present invention relates to trip beam assemblies for use with earth working tools such as moldboard plows.
2 Prior Art
In the prior art relating to tripping beams, various efforts have been made to provide a plow that will float over ordinary obstacles, and will trip very high when it encounters a large obstacle, or an obstacle that tends to hook the plow bottom.
Floating plow beams that trip in two different modes, one to float over obstacles and the other for high clearance were known prior to this time. My own U.S. Pat. No. 3,052,308 shows a type of plow trip which floats over ordinary rocks in the field, and which trips for high clearance when certain obstacles were encountered.
Further improvements of this type of device include my U.S. Pat. Nos. 3,468,382 and 3,550,690.
U.S. Pat. No. 3,321,027 involves such a linkage which places great emphasis on the ability of folding links to be reset prior to the entry of the plow back to its working position. Means are specifically provided in this patent for insuring that reset occurs before the unit returns to the ground.
Another type of prior art device providing a tripping action for a cultivator shovel is shown in Canadian Pat. No. 635,406, Issued Jan. 30, 1962 to Ivor C. Rogers.
Thus, while efforts have been made to provide satisfactory plow or earth working tool operations particularly where the ground includes rocks, stumps or other obstacles, the prior art devices have had drawbacks in relation to their ability to provide reliable tripping in all types of operation as well as providing low cost manufacture.
A reliable tripping linkage, which provides high clearance when an obstacle is encountered is shown in my copending application Ser. No. 606,726, Filed Aug. 21, 1975. The present device incorporates a folding linkage arranged in a manner similar to that shown in my application Ser. No. 606,726, but by modifications, which will become apparent. The present device permits floating over smaller or rounded obstacles and in this way significantly reduces the number of times that the plow bottom must trip fully.
U.S. Pat. No. 3,565,180 shows a tripping plow, and includes a stop block with an off center hole, but it is not used in a toggle linkage.